[ RadSafe ] Biologic Response to Ionizing Radiation

Mon May 9 10:37:23 CDT 2011

A comment from the peanut gallery: how could we NOT be evolved to deal 
with damage from ionizing radiation? We have been marinading in the 
stuff for over 4 billion years now.

-Tom

On 05/09/2011 11:34 AM, Ludwig E. Feinendegen wrote:
> Hi All:
>
> A good summary of the current state of knowledge is presented in the paper
>
> BIOLOGICAL CONSEQUENCES AND HEALTH RISKS OF LOW-LEVEL EXPOSURE TO IONIZING RADIATION: COMMENTARY ON THE WORKSHOP
> Ludwig E. Feinendegen,* Antone L. Brooks,? and William F. Morgan?by
>
> Ludwig E. Feinendegen, Antone L. Brooks, and William F. Morgan
>
> in
>
> Health Phys. 100(3):247-259; 2011
>
> Best regards;
>
> Ludwig Feinendegen
>
>
>
>
> ----- Original Message -----
> From: "Howard"<howard.long at comcast.net>
> To: "The International Radiation Protection (Health Physics) MailingList"<radsafe at health.phys.iit.edu>
> Cc: "The International Radiation Protection (Health Physics) Mailing List"<radsafe at health.phys.iit.edu>
> Sent: Monday, May 09, 2011 4:50 PM
> Subject: [ RadSafe ] Biologic Response to Ionizing Radiation
>
>
>> Chris,
>> Indeed, "Higher forms of life are not possible without vigorous and efficient
>> DNA repair mechanisms".
>> Feinendigan and Pollycove presented studies showing something like 10 exponent biologic repair response (hormesis) in irradiated mice, something akin to immunization with viral vaccines (think smallpox) or allergy shots.
>> I hope they will comment.
>> Howard Long
>>
>> On May 9, 2011, at 3:13 AM, Doug Huffman<doug.huffman at wildblue.net>  wrote:
>>
>>> Well said!  Thank you.  Tersely too.
>>>
>>> On 5/9/2011 02:32, Chris Hofmeyr wrote:
>>>> Hi, Bill,
>>>>
>>>> Being alive of course incurs a 100% integrated risk irrespective of the meaning
>>>> of safety!. However, the LNT crowd treats living organisms as dead matter, i.e.
>>>> with no biological response to (radiation) damage. That is most probably a poor
>>>> assumption. Higher forms of life are not possible without vigorous and efficient
>>>> DNA repair mechanisms. Aging probably results from the fact that the repair
>>>> mechanisms are not quite 100% effective to begin with and weaken with time.
>>>> Regards,
>>>> Chris
>>>> chris.hofmeyr at webmail.co.za
>>>>
>>>> On Fri, 6 May 2011 13:42:16 -0400 "Bill Prestwich"<prestwic at mcmaster.ca>  wrote
>>>>
>>>>> Hi John,
>>>>>
>>>>> This is a longer thing I sent regarding a local discussion here at Mac
>>>>> arising from the 86 billion radsafe posting.
>>>>>
>>>>> I don't think the radsafe posting was meant to be a rigorous discourse, and
>>>>> neither is this reply. To set the record straight, the Linear No Threshold
>>>>> (LNT) theory is really an assumption that the probability of a harmful
>>>>> effect resulting from  exposure to ionizing radiation is directly
>>>>> proportional to the effective dose. Ionizing radiation is the capitalist
>>>>> form of radiation which evicts electrons from their molecules. Dose is
>>>>> defined as the ratio of energy deposited by the radiation to the mass of the
>>>>> object in which it is deposited. The adjective effective indicates that a
>>>>> crude attempt has been made to take into account the variability of
>>>>> effectiveness of different radiation types and the variability of radiation
>>>>> sensitivity of different organs. It is not possible to make a quantitative
>>>>> assessment for the scenario described in the article.
>>>>>             The logical conclusion of the LNT, which has not been validated
>>>>> empirically, is that any finite dose produces a finite probability for harm.
>>>>> This is incorrectly translated into the statement that science has shown
>>>>> there is no safe level of radiation. This is an Orwellian tactic which takes
>>>>> advantage of two facts. First there is no scientific definition of safe, and
>>>>> the proponents are implying it is zero probability of harm. Second the
>>>>> concept of safe is generally treated as binary. Something that is not safe,
>>>>> ie is unsafe, is dangerous. Hence the implication is that any radiation
>>>>> exposure is dangerous. Now, given that we live on a radioactive planet, eat
>>>>> radioactive food, breathe radioactive air, have radioactive bodies and are
>>>>> bombarded by radiation from outer space, this means we must conclude that
>>>>> the act of living is dangerous.
>>>>>             This does however open up an interesting legal possibility. It
>>>>> seems to me humanity has a right to launch a class action suit against the
>>>>> religious organizations as representatives of God who, after all, bears the
>>>>> ultimate responsibility for all this.
>>>>>             Finally the general consensus is that it is not possible to
>>>>> obtain statistically significant empirical data with which to test the LNT
>>>>> assumption in the range of dose equivalents below the regulatory limits. The
>>>>> situation is similar to attempting to detect a signal buried in noise
>>>>> without the ingenious signal to noise enhancement techniques employed by our
>>>>> electrical engineering colleagues. However, given that the assumption
>>>>> ignores the known complexities of biological responses and fails to predict
>>>>> observed radiobiological phenomena it is clear that the assumption does not
>>>>> have a substantial scientific basis.
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